Means for cleaning heat conductive conduits of a heat exchanger

ABSTRACT

Means for cleaning heat conductive conduits in a heat exchanger which comprises an inlet conduit for introducing cooling water and an outlet conduit for exhausting the cooling water, said cleaning means including means provided in said cooling water outlet conduit for recovering resilient balls, means for separating the resilient balls from the cooling water, fluid driven pump means for drawing cooling water containing the resilient balls, means for introducing the resilient balls into the conduits, and further conduits for connecting the cooling water inlet conduit with the other components of the cleaning means.

United States Patent 11 1 Kumagai 1451 May 13,1975

1 1 MEANS FOR CLEANING HEAT CONDUCTIVE CONDUITS OF A HEAT EXCHANGER [75] Inventor: Yoshio Kumagai, Takaha gi, Japan [73] Assignee: Hitachi, Ltd., Japan [22] Filed: Mar. 20, 1973 [21] Appl. No.: 343,036

[30] Foreign Application Priority Data Mar. 24, 1972 Japan 47-28949 [52] US. Cl. 165/95 [51] Int. Cl. F28g 1/12 [58] Field of Search l65/5.95

[56] References Cited UNITED STATES PATENTS 3,215,195 11/1965 Treplim 165/95 3,291,197 12/1966 Kollerup 165/95 X FOREIGN PATENTS OR APPLICATIONS Germany 165/94 Primary ExaminerCharles J. Myhre Assistant ExaminerTheophil W. Streule, Jr. Attorney, Agent, or FirmCraig & Antonelli [57] ABSTRACT Means for cleaning heat conductive conduits in a heat exchanger which comprises an inlet conduit for introducing cooling water and an outlet conduit for exhausting the cooling water, said cleaning means including means provided in said cooling water outlet conduit for recovering resilient balls, means for separating the resilient balls from the cooling water, fluid driven pump means for drawing cooling water containing the resilient balls, means for introducing the resilient balls into the conduits, and further conduits for connecting the cooling water inlet conduit with the other components of the cleaning means.

12 Claims, 5 Drawing Figures MEANS FOR CLEANING HEAT CONDUCTIVE CONDUITS OF A HEAT EXCHANGER The present invention relates to an improvement of means for cleaning inner wall surfaces of heat conductive conduits in a heat exchanger by circulating deformable bodies such as resilient balls through the conduits.

Generally, in a heat exchanger, it has been a common practice for ensuring a high heat exchanging performance to use resilient balls such as foam rubber balls to mechanically remove formed on the inner wall surfaces of heat conductive conduits in heat exchangers by forcing the balls to pass through the conduits under the pressure of coolant in rubbing contact with the inner walls of the conduits. Conventionally, means has been provided between coolant water supply or inlet conduit means and coolant water exhaust or outlet conduit means of a heat exchanger for recovering the foam rubber balls which have been forced to circulate through the conduits in the heat exchanger. The recovered balls are passed through circulating passage means which has ball circulating pump means disposed therein.

Recently, in view of the fact that it is very difficult in a steam power plant to obtain a sufficient amount of sea water as a coolant, a multi-stage pressure type heat exchanger has been used since it requires less amount of coolant. A similar type of heat exchanger is also used in a sea-water refreshing apparatus. In such a type of multi-stage pressure type heat exchanger, the load on a the conduit means is so increased that the temperature difference between the inlet and outlet of the heat exchanger is increased as compared with a conventional condenser. Therefore, when a large amount of outlet water is mixed with inlet cold water, the cooling effect of the heat exchanger is remarkably decreased.

The sponge ball circulating pump used in the conduit cleaning device is usually of such a type that has a low pumping head and a high output capacity, because it must allow the sponge balls to be circulated without their being damaged. When such a type of pump is used for circulating the sponge balls, it is very difficult to decrease the amount of outlet water which is discharged with the sponge balls because the amount of the outlet water is dependent on the inner diameter of the conduits in the heat exchanger. Therefore, it has been considered that it is difficult to employ the sponge ball type conduit cleaning device in a multistage pressure type heat exchanger in which a less amount of coolant is circulated.

An object of the present invention is to prevent a large amount of hot water discharged together with resilient balls from flowing into the flow of inlet coolant water, and thus preventing the cooling efficiency of a heat exchanger from being decreased.

Another object of the present invention is to separate a substantial amount of the coolant which is discharged from a heat exchangerfrom the resilient balls, in order that least amount of hot water discharged from the heat exchanger is allowed to flow into the inlet coolant water.

A further object of the present invention is to draw resilient balls discharged from a heat exchanger with the least amount of coolant and supply them into the flow of inlet coolant, whereby the least amount of hot water discharged from the heat exchanger is recirculated by being mixed in the cold coolant.

A still further object of the present invention is to provide means for separating a substantial part of the hot coolant water from a mixture of coolant water and resilient balls discharged from a heat exchanger.

According to the present invention, there is provided means for cleaning conduits of a heat exchanger having inlet and outlet means respectively supplying and discharging a coolant into and from the heat exchanger, said cleaning means comprising communicating passage means between said inlet and outlet means of said heat exchanger for allowing conduit cleaning resilient balls to recirculate through the heat exchanger and the communicating passage means, means for separating the resilient balls from coolant discharged from the heat exchanger, and pump means for drawing the balls and supplying them into the flow of coolant at the inlet means of the heat exchanger.

FIG. 1 is a circuit diagram of a conventional heat exchanger cleaning system having means for recirculating sponge balls through conduits in the heat exchanger;

FIG. 2 is a circuit diagram showing one embodiment of the present invention which includes means for separating resilient balls from outlet coolant water and pump means for drawing the resilient balls;

FIG. 3 is a diagrammatical view of the pump means used in the system shown in FIG. 2;

FIG. 4 is a diagrammatical view of the resilient ball separating means used in the system shown in FIG. 2; and,

FIG. 5 is a circuit diagram showing another embodiment of the present invention.

In order that the invention is fully understood, reference will first be made to FIG. 1 which shows a typical example of a conventional heat exchanger cleaning system. The illustrated heat exchanger includes a water feed pump 1 for feeding water or coolant through inlet conduits 2 and 3 into a heat exchanger 4. The heat exchanger 4 has a plurality of conduits 11 through which water or coolant is passed from the inlet conduit 3 to an outlet conduit 5. As the water is passed through the conduits 11 in the heat exchanger 4, heat is transferred to the water from the hot medium which is also passed through the heat exchanger 4. The coolant or water is then introduced into sponge ball recovering means 7 which includes lattice means 13 for catching sponge balls contained in the coolant. As is well known in the art, the sponge balls are used for removing foreign materials deposited on the inner wall surfaces of the conduits 11 in the heat exchanger by being circulated therethrough together with the coolant. The water separated from the sponge balls at the recovering means 7 is then discharged through a conduit 6. The sponge balls caught by the lattice 13 are drawn by means of a pump 10 together with a portion of the coolant through a conduit 8 and discharged through a conduit 12 into 1 the conduit 3. Sponge ball feeding means 9 are provided in the conduit 8 for normally storing fresh sponge balls therein but supplying them into the conduit when it is desired to clean the heat exchanger. Thus, the sponge balls are recirculated through the circulation system as described above. The pump 10 is of a bladeless type so as to prevent the sponge balls from being damaged.

In operation, the sponge balls are heated at the heat exchanger when they are caught by the recovering means 7. The hot sponge balls are then drawn by the pump 10 together with a certain amount such as l to 5 percentage of hot water at the outlet side of the heat exchanger, and discharged into the coolant at the inlet side. Thus, the inlet water receives heat from the sponge balls and the hot water drawn with the sponge balls and therefore the efficiency of heat exchange is correspondingly decreased. In a multi-stage pressure type heat exchanger in which a smaller amount of cooling water is passed, the effect of the hot water recirculated into the inlet side of the heat exchanger becomes so significant that it remarkably decreases the heat exchanging efficiency of the heat exchanger. Thus, it will be understood that, when the sponge ball recirculating type cleaning system is employed in a multi-stage pressure type heat exchanger, it is essential to minimize the amount of water drawn from the outlet side of the heat exchanger together with the sponge balls. However, it should be noted that the diameter of the sponge ball is dependent on the inner diameter of the conduit 11 in the heat exchanger and that the pump must be of such a type that can allow the sponge balls to pass therethrough without being damaged. Therefore, the pump 10 must be of such a type that has a large output capacity but a small pumping head. It should further be noted that the amount of water drawn through the conduit 8 is also dependent on the inner diameter of the conduit 11 in the heat exchanger 4. Therefore, it is impractical to reduce the amount of water drawn through the conduit 8 as far as the pump 10 of the aforementioned type is used. Thus, it has been very difficult to employ the sponge ball recirculating type cleaning system in a multi-stage pressure type heat exchanger in which a smaller amount of water is passed.

An embodiment of the present invention will now be described. Referring to FIG. 2, the heat exchanging system embodying the present invention includes a water feeding pump 1 which feeds water or coolant through conduits 2 and 3 into a heat exchanger 4. The heat exchanger 4 includes a plurality of conduits 11 through which the water is passed and discharged into an outlet conduit 5. Sponge ball recovering means 7 is provided in the conduit 5 and has a lattice 13 provided therein for catching sponge balls or resilient balls contained in the cooling water. Thus, the sponge balls are taken out of the conduit 5 through a conduit 8 together with a portion of the cooling water at the outlet side of the heat exchanger 4. In the conduit 8, there is provided a sponge ball separator for removing a substantial part of the water from the sponge balls. The removed water is then discharged through conduits 27 and 29 into a discharge conduit 6. For this purpose, a pump 28 is provided at the junction of the conduits 27 and 29. The sponge balls are then drawn from the separator 20 through a conduit 21 into a jet pump 22 together with a minimum amount of water.

Referring now to FIG. 3, the jet pump 22 comprises a nozzle portion 31 for injecting a water jet into the pump, an intake section 33 for drawing fluid or fluidized material thereinto, and a throat section 32 for directing the fluid from the nozzle portion 31 and the intake section 33 to the exterior of the pump. The nozzle portion 31 of the pump 22 is connected through a conduit 25, a pump 24 and a conduit 23 with the conduit 2. Thus, in operation, the pump 22 is supplied with injection of water jet from the conduit 2 through the conduits 23 and 25 by means of the pump 24. The water jet thus produced is effective to draw the sponge balls with a small amount of the cooling water through the intake section 33 and direct them to the throat section 32. The sponge balls are then introduced through conduits 26 and 30 into the coolant supply conduit 2 to be recirculated through the heat exchanger 4. Sponge ball feeding means 9 is provided at the junction of the conduits 26 and 30 for feeding the sponge balls into the conduit 30 when desired. As is well known in the art, the sponge balls discharged into the conduit 2 are passed through the conduits 11 in the heat exchanger 4 in rubbing contact with the inner surfaces of the conduits 11 to remove scale or other foreign material deposited thereon.

In the illustrated embodiment, the jet pump 22 has a ratio R of the area A of the throat section 32 to the area A of the nozzle portion 31 which is substantially equal to one (R A /A E l) in view of the relation between the amount of flow of the water jet Qand that Q of the water taken into the pump through the intake section 33. It has been found that, when the diameter of the nozzle portion 31 is close to that of the throat section 32, the amount of water taken into the pump through the intake section is decreased with respect to the amount of the injected water jet so that the amount of hot water passed through the pump 22 into the inlet conduit 2 can be minimized.

FIG. 4 shows an example of the sponge ball separator 20. As shown in the drawings, the separator 20 comprises a housing 35 which is provided with a conduit 27 for directing the water separated from the sponge balls into the discharge conduit 6. In the housing 35, there is disposed a screen 40 which is connected on one hand with the conduit 8 and on the other hand with the conduit 21. The sponge balls are separated from the substantial part of water by the screen 40 and passed through the conduit 21 into the pump 22 together with minimum amount of water to be recirculated through the heat exchanger 4.

FIG. 5 shows another embodiment of the present invention in which the jet pump 22 is eliminated. The arrangement of this embodiment is substantially identical to the previous embodiment so that the details of the arrangement will not be described. According to this embodiment, a bladeless pump 45 of a known type is used in the place of the jet pump 22 in the previous embodiment. A branch conduit 41 is provided in the inlet conduit 2 and connected through a pressure reduction valve 42 with a conduit 43 which is in turn connected with a line 21 between the sponge ball separator 20 and the pump 45. As in the previous embodiment, the pump 45 is connected through a conduit 26 with a sponge ball feeding means 9 and therefrom through a conduit 30 with the inlet conduit 2. In this embodiment, a part of the coolant from the conduit 2 is drawn through the conduit 41, reduced in pressure by the pressure reduction valve 42 and taken through the conduit 43 into the pump 45 together with the sponge balls from the separator 20. According to this embodiment, the reduced pressure in the conduit 43 effectively draws the sponge balls from the separator 20.

Although the invention has been described as being applied to a single stage heat exchanger, it should of course be noted that the invention can equally be applied to any type of multi-stage heat exchangers and also to any type of apparatus having heat conductive conduits such as a multi-stage flush type evaporator. Thus, the invention is not limited to the details of the illustrated embodiments but various changes and modifications can be made without departing from the scope of the appended claims.

I claim:

1. Cleaning apparatus for cleaninng heat conductive conduit means of a heat exchanger of the type having heat conductive conduit means, inlet conduit means for supplying heat exchange fluid to said heat conductive conduit means, and outlet conduit means for exhausting the heat exchange fluid from the heat conductive conduit means, said cleaning apparatus comprising:

recovering means provided in said outlet conduit means for recovering conduit cleaning elements present in said heat exchange fluid, separating means connected with the recovering means in fluid flow relationship for separating a portion of the heat exchange fluid from the conduit cleaning elements, and suction means receiving the conduit cleaning elements and remaining heat exchange fluid from said separating means for directing said conduit cleaning elements and remaining heat exchange fluid from the separating means into said inlet conduit means,

wherein said suction means comprises a suction pump including nozzle means for injecting fluid into said pump so as to produce a suction pressure portion in said suction pump, suction-inlet means for drawing the conduit cleaning elements with the remaining heat exchange fluid from the separating means under the influence of the suction pressure produced by said nozzle means, and an outlet section connected with said inlet conduit means for discharging the conduit cleaning elements into said inlet conduit means.

2. Cleaning apparatus in accordance with claim 1 which further comprises a branched conduit branched from the inlet conduit means and connected with the nozzle means of the suction pump, and additional pump means in said branched conduit for pumping heat exchange fluid from said inlet conduit means to said suction pump to be injected into said nozzle means.

3. Cleaning apparatus in accordance with claim 1, which further includes an exhaust conduit containing pump means therein provided in fluid flow relationship with said separating means for exhausting heat exchange fluid separated from the conduit cleaning elements.

4. Cleaning apparatus in accordance with claim 3, in which said separating means comprises a receiving conduit for receiving the conduit cleaning elements from the recovering means, a directing conduit for directing the conduit cleaning elements into a pump, a member connecting said receiving and directing conduits together and having a plurality of openings of such dimensions that do not allow the conduit cleaning elements to pass therethrough, a conduit for exhausting heat exchange fluid from said separating means, and a housing for supporting said conduits and enclosing said member, whereby a substantial portion of heat exchange fluid is removed from the conduit cleaning elements.

5. Cleaning apparatus in accordance with claim 4, wherein said conductive cleaning elements comprise resilient balls.

6. Cleaning apparatus for cleaning heat conductive conduits of a heat exchanger of the type comprising an 6 inlet conduit for supplying heat exchange fluid to the heat conductive conduits, and an outlet conduit for exhausting used heat exchanger fluid at elevated temperatures from the heat conductive conduits, said cleaning apparatus comprising:

recovering means connected to the outlet conduit for recovering cleaning elements present in the heat exchange fluid and for removing at least a portion of the used heat exchange fluid therefrom, a first conduit in fluid flow communication with the recovering means for permitting the flow therefrom of the cleaning elements together with the remainder of the heat exchange fluid, a second conduit in fluid flow communication with the inlet conduit for supplying thereto the cleaning elements flowing through the first conduit, a separator comprising a member communicating with both the first and second conduits and formed with a multiplicity of openings small enough to avoid the escape of the cleaning elements therethrough, a container enclosing the member and provided with an exhaust conduit for separating used heat exchange fluid from the cleaning elements in said member, and cleaning element-supplying means for supplying the cleaning elements to the inlet conduit under the influence of suction pressure, said cleaning element-supplying means being installed in the second conduit in such a manner as to reduce the fluid pressure therein to a level lower than that in the first conduit, and thereby draw the the cleaning elements therefrom together with a small amount of heat exchange fluid and direct the cleaning elements thus drawn with an increased fluid pressure to the inlet conduit, wherein the cleaning element supply means is arranged to permit substantially continuous circulation of the cleaning elements through the cleaning apparatus to clean the heat conductive conduits.

7. Cleaning apparatus in accordance with claim 6, in which said supplying means comprises a branch conduit branching from the inlet conduit means and connected with a fluid flow line between said separating means and a pump means, and pressure reduction valve means provided in said branch conduit for providing in conjunction with said pump means a suction pressure in said fluid flow line so'as to circulate the conduit cleaning elements and remaining heat exchange fluid from said separating means to said inlet conduit means.

8. Cleaning apparatus in accordance with claim 6, wherein the cleaning element-supplying means is a pump which has a pipe branched from the inlet conduit, the branched pipe being in fluid flow communication with the second conduit and being interconnected with a reducing valve in such a manner that the fluid pressure in the second conduit is made lower than the pressure in the first conduit.

9. Cleaning apparatus in accordance with claim 6, wherein the exhaust conduit of the separator is connected in fluid flow relationship with the outlet conduit, and pump means are installed in the exhaust conduit to pump the heat exchange fluid separated from the cleaning elements by the separator to said outlet conduit.

10. Cleaning apparatus for cleaning heat conductive conduits of a heat exchanger of the type comprising an inlet conduit for supplying heat exchange fluid to the heat conductive conduits, and an outlet conduit for exhausting used heat exchange fluid at elevated temperatures from the heat conductive conduits, said cleaning apparatus comprising: recovering means connected to the outlet conduit for recovering cleaning elements present in the heat exchange fluid and used in cleaning the heatconductive conduits and for removing a portion of the used heat exchange fluid therefrom, a first conduit in fluid flow communication with the recovering means for permitting the flow therefrom of the cleaning elements together with the remainder of the heat exchange fluid, a second conduit in fluid flowcommunication with the inlet conduit for supplying thereto the cleaning elements flowing through the first conduit, a

ing elements to the inlet conduit under the influence of suction pressure, said cleaning element-supplying means being installed in the second conduit in such a manner as to reduce the fluid pressure therein to a level lower than that in the first conduit, and thereby draw the cleaning elements therefrom together with a small amount of heat exchange fluid and direct the cleaning elements thus drawn with an increased fluid pressure to the inlet conduit, wherein the cleaning element-supplying means is a jet pump which has nozzle means for injecting fluid into thepump to produce a low-pressure portion therein in such a manner that the pressure difference between the low-pressure portion and the rest of the pump draws the cleaning elements together with the heat exchange fluid from a suction side of the pump in communication with the separator via the second conduit, and then discharges the cleaning elements from a delivery side of the pump which is in communication with the water-supplying inlet conduit via the second conduit. 11. Cleaning apparatus in accordance with claim 10, wherein the nozzle means is connected in fluid flow relationship with a pipe branched from the inlet conduit, and additional pump means is installed in the branched pipe to use a part of the heat exchange fluid as injection fluid in saidjet pump.

12. Cleaning apparatus for cleaning heat conductive conduits of a heat exchanger of the type comprising an inlet conduit for supplying cooling water to the heat conductive conduits and an outlet conduit for exhausting used cooling water at elevated temperatures from the heat conductive conduits, said cleaning apparatus comprising:

recovering means connected to the outlet conduit for recovering resilient balls used in cleaning the heat conductive conduits and for removing most of the used cooling water at elevated temperatures, a first conduit in communication with the recovering means for circulating therefrom the resilient balls together with the remainder of the used water, a second conduit in communication with the inlet conduit for supplying thereto the resilient balls being circulated through the first conduit, a separator comprised of a member communicating with both the first and second conduits and formed with a multiplicity of openings small enough to avoid the escape of the resilient balls therethrough, a container accommodating the member and provided with an ex-- having suction and delivery ports and a nozzle portion for injecting fluid into the pump, said jet pump being installed in the second conduit line in such a manner that the fluid injected by the nozzle portion into the pump produces a lowpressure portion where the pressure difference between the low-pressure portion and the rest of the pump draws the resilient balls together with the used water from the suction side of the pump which is in communication with the separator via the second conduit and then discharges the balls from the delivery side of the pump which is in communication with the water-supplying inlet conduit via the second conduit, a branched pipe forcommunicating the nozzle portion of the jet pump with the inlet conduit, and a second'pump installed in the branched pipe so as to inject a part of the cooling water as an injection fluid into the jet pump. 

1. Cleaning apparatus for cleaninng heat conductive conduit means of a heat exchanger of the type having heat conductive conduit means, inlet conduit means for supplying heat exchange fluid to said heat conductive conduit means, and outlet conduit means for exhausting the heat exchange fluid from the heat conductive conduit means, said cleaning apparatus comprising: recovering means provided in said outlet conduit means for recovering conduit cleaning elements present in said heat exchange fluid, separating means connected with the recovering means in fluid flow relationship for separating a portion of the heat exchange fluid from the conduit cleaning elements, and suction means receiving the conduit cleaning elements and remaining heat exchange fluid from said separating means for directing said conduit cleaning elements and remaining heat exchange fluid fRom the separating means into said inlet conduit means, wherein said suction means comprises a suction pump including nozzle means for injecting fluid into said pump so as to produce a suction pressure portion in said suction pump, suction-inlet means for drawing the conduit cleaning elements with the remaining heat exchange fluid from the separating means under the influence of the suction pressure produced by said nozzle means, and an outlet section connected with said inlet conduit means for discharging the conduit cleaning elements into said inlet conduit means.
 2. Cleaning apparatus in accordance with claim 1 which further comprises a branched conduit branched from the inlet conduit means and connected with the nozzle means of the suction pump, and additional pump means in said branched conduit for pumping heat exchange fluid from said inlet conduit means to said suction pump to be injected into said nozzle means.
 3. Cleaning apparatus in accordance with claim 1, in which said suction means comprises a branch conduit branching from the inlet conduit means and connected with a fluid flow line between said separating means and a pump means, and pressure reduction valve means provided in said branch conduit for providing in conjunction with said pump means a suction pressure in said fluid flow line so as to circulate the conduit cleaning elements and remaining heat exchange fluid from said separating means to said inlet conduit means.
 4. Cleaning apparatus in accordance with claim 1, which further includes an exhaust conduit containing pump means therein provided in fluid flow relationship with said separating means for exhausting heat exchange fluid separated from the conduit cleaning elements.
 5. Cleaning apparatus in accordance with claim 1, in which said separating means comprises a receiving conduit for receiving the conduit cleaning elements from the recovering means, a directing conduit for directing the conduit cleaning elements into a pump, a member connecting said receiving and directing conduits together and having a plurality of openings of such dimensions that do not allow the conduit cleaning elements to pass therethrough, a conduit for exhausting heat exchange fluid from said separating means, and a housing for supporting said conduits and enclosing said member, whereby a substantial portion of heat exchange fluid is removed from the conduit cleaning elements.
 6. Cleaning apparatus for cleaning heat conductive conduits of a heat exchanger of the type comprising an inlet conduit for supplying heat exchange fluid to the heat conductive conduits, and an outlet conduit for exhausting used heat exchanger fluid at elevated temperatures from the heat conductive conduits, said cleaning apparatus comprising: recovering means connected to the outlet conduit for recovering cleaning elements present in the heat exchange fluid and for removing at least a portion of the used heat exchange fluid therefrom, a first conduit in fluid flow communication with the recovering means for permitting the flow therefrom of the cleaning elements together with the remainder of the heat exchange fluid, a second conduit in fluid flow communication with the inlet conduit for supplying thereto the cleaning elements flowing through the first conduit, a separator comprising a member communicating with both the first and second conduits and formed with a multiplicity of openings small enough to avoid the escape of the cleaning elements therethrough, a container enclosing the member and provided with an exhaust conduit for separating used heat exchange fluid from the cleaning elements in said member, and cleaning element-supplying means for supplying the cleaning elements to the inlet conduit under the influence of suction pressure, said cleaning element-supplying means being installed in the second conduit in such a manner as to reduce the fluid pressure therein to a level lower than that in the first conduit, and thereby draw the the cleaning elemEnts therefrom together with a small amount of heat exchange fluid and direct the cleaning elements thus drawn with an increased fluid pressure to the inlet conduit, wherein the cleaning element supply means is arranged to permit substantially continuous circulation of the cleaning elements through the cleaning apparatus to clean the heat conductive conduits.
 7. Cleaning apparatus for cleaning heat conductive conduits of a heat exchanger of the type comprising an inlet conduit for supplying heat exchange fluid to the heat conductive conduits, and an outlet conduit for exhausting used heat exchange fluid at elevated temperatures from the heat conductive conduits, said cleaning apparatus comprising: recovering means connected to the outlet conduit for recovering cleaning elements present in the heat exchange fluid and used in cleaning the heat conductive conduits and for removing a portion of the used heat exchange fluid therefrom, a first conduit in fluid flow communication with the recovering means for permitting the flow therefrom of the cleaning elements together with the remainder of the heat exchange fluid, a second conduit in fluid flow communication with the inlet conduit for supplying thereto the cleaning elements flowing through the first conduit, a separator comprising a member communicating with both the first and second conduits and formed with a multiplicity of openings small enough to avoid the escape of the cleaning elements therethrough, a container enclosing the member and provided with an exhaust conduit for separating used heat exchange fluid from the cleaning elements in said member, and cleaning element-supplying means for supplying the cleaning elements to the inlet conduit under the influence of suction pressure, said cleaning element-supplying means being installed in the second conduit in such a manner as to reduce the fluid pressure therein to a level lower than that in the first conduit, and thereby draw the cleaning elements therefrom together with a small amount of heat exchange fluid and direct the cleaning elements thus drawn with an increased fluid pressure to the inlet conduit, wherein the cleaning element-supplying means is a jet pump which has nozzle means for injecting fluid into the pump to produce a low-pressure portion therein in such a manner that the pressure difference between the low-pressure portion and the rest of the pump draws the cleaning elements together with the heat exchange fluid from a suction side of the pump in communication with the separator via the second conduit, and then discharges the cleaning elements from a delivery side of the pump which is in communication with the water-supplying inlet conduit via the second conduit.
 8. Cleaning apparatus in accordance with claim 6, wherein the cleaning element-supplying means is a pump which has a pipe branched from the inlet conduit, the branched pipe being in fluid flow communication with the second conduit and being interconnected with a reducing valve in such a manner that the fluid pressure in the second conduit is made lower than the pressure in the first conduit.
 9. Cleaning apparatus in accordance with claim 6, wherein the exhaust conduit of the separator is connected in fluid flow relationship with the outlet conduit, and pump means are installed in the exhaust conduit to pump the heat exchange fluid separated from the cleaning elements by the separator to said outlet conduit.
 10. Cleaning apparatus in accordance with claim 7, wherein the nozzle means is connected in fluid flow relationship with a pipe branched from the inlet conduit, and additional pump means is installed in the branched pipe to use a part of the heat exchange fluid as injection fluid in said jet pump.
 11. Cleaning apparatus for cleaning heat conductive conduits of a heat exchanger of the type comprising an inlet conduit for supplying cooling water to the heat conductive conduits and an outlet conduit for exhausting used cooling water at elevated temperatures from the heat cOnductive conduits, said cleaning apparatus comprising: recovering means connected to the outlet conduit for recovering resilient balls used in cleaning the heat conductive conduits and for removing most of the used cooling water at elevated temperatures, a first conduit in communication with the recovering means for circulating therefrom the resilient balls together with the remainder of the used water, a second conduit in communication with the inlet conduit for supplying thereto the resilient balls being circulated through the first conduit, a separator comprised of a member communicating with both the first and second conduits and formed with a multiplicity of openings small enough to avoid the escape of the resilient balls therethrough, a container accommodating the member and provided with an exhaust conduit for drawing the used water away from the resilient balls in said member, said exhaust conduit of the separator being in communication with the outlet conduit, a first pump installed in the exhaust conduit to exhaust the used water separated by the separator, a jet pump having suction and delivery ports and a nozzle portion for injecting fluid into the pump, said jet pump being installed in the second conduit line in such a manner that the fluid injected by the nozzle portion into the pump produces a lowpressure portion where the pressure difference between the low-pressure portion and the rest of the pump draws the resilient balls together with the used water from the suction side of the pump which is in communication with the separator via the second conduit and then discharges the balls from the delivery side of the pump which is in communication with the water-supplying inlet conduit via the second conduit, a branched pipe for communicating the nozzle portion of the jet pump with the inlet conduit, and a second pump installed in the branched pipe so as to inject a part of the cooling water as an injection fluid into the jet pump.
 12. Cleaning apparatus in accordance with claim 1, wherein said conductive cleaning elements comprise resilient balls. 